塔里木盆地顺托果勒地区北东向走滑断裂带的油气勘探意义

Significance of oil and gas exploration in NE strike-slip fault belts in Shuntuoguole area of Tarim Basin

古隆起碳酸盐岩风化壳领域是多年来塔里木盆地油气勘探发现的重要领域。近年来,在塔中、塔北古隆起之间的顺托果勒低隆、斜坡区,通过新的地震资料识别出一系列走滑断裂带,且钻井揭示其具有较好的含油气性,相继在顺南、顺托、顺北实现重大油气突破。顺托果勒地区北东向左行走滑断裂带在构造样式上具有"纵向分层变形、深部主滑移带沿走向分段变形"的特征,上奥陶统及其之上的碎屑岩层系多发育雁列式正断层,其下部对应于发育在碳酸盐岩层系的走滑断层主滑移带。受斜列侧接部位局部应力场改变的影响,走滑断裂带深部通常表现为拉分负花状、压隆正花状及平移平直状3类样式。多期活动的系列北东向走滑断裂带形成了规模较大的碳酸盐岩缝洞体系,为后期埋藏溶蚀改造形成规模储层和油气运聚均提供了有利条件,具有明显的"控储、控藏、控富"特征。在这种奥陶系发育较为齐全的低隆斜坡区呈现出沿断裂带大面积富含油气的勘探形势,具有不同于古隆起暴露剥蚀区风化壳领域的油气成藏模式,使得"塔河之外找塔河"成为可能,已初步落实轻质油资源量12×10~8t,将成为中石化塔里木探区"十三五"期间增储建产的主战场。

For years,the carbonate weathering crust of paleo-uplifts has been a major exploration domain in Tarim Basin.A series of strike-slip fault belts were recognized with updated seismic data in the Shuntuoguole low uplift and slopes between the Tazhong and Tabei paleo-uplifts in Tarim Basin.Drilling data from the area revealed great oil or gas potential,and later significant oil and gas discoveries in the south（also called Shunnan） and north（also called Shunbei） parts as well as Shuntuo of the area verified the revelation.The left lateral strike-slip fault belts of north-east trending in the area are characterized by ＂layered deformation in vertical direction and segmented deformation along strike of the major slip zone in the deep＂.Echelon normal faults are common in the clastic rocks in the upper Ordovician and layers above it.The lower Ordovican corresponds to the major strike-slip zone developed in carbonates.Local stress field variation in echelon and side joint parts had shaped the strike-slip fault belts into three types of structural patterns：pull-apart negative flower pattern,compressive uplifting positive flower pattern and straight parallel displacement.The strike-slip fault belts with multiple stages of activities formed massive carbonate fracture-vug systems,which provided favorable conditions for the migration and accumulation of oil and gas after a later burial and dissolution process and showed obvious features of＂controlling reservoir formation,hydrocarbon accumulation and enrichment＂.The slope zones of low-uplifts with fully developed Ordovician feature in extensive hydrocarbon accumulation along the fault belts,which is different from those in weathering crust of the exposed and denuded paleo-uplifts.The understanding of the new hydrocarbon accumulation pattern made it possible to obtain another Tahe-like discovery.Currently,about 1.2 billion tons of light oil resources have been confirmed,making the area a main ＂battlefield＂ of achieving the goal of reserve growth and productivity constructionof oil and gas during the 13 th-Five-Year-Plan Period by Sinopec.